The purpose of this thesis is to provide a review and discussion of the current literature on auditory processing, speech discrimination, word recognition, and early lexical representations in children with normal hearing and those with hearing impairment in addition to identifying areas in which current research is lacking. This information is needed to consider potential interactions between various factors affecting the development of spoken word recognition. This will also provide a starting point for identifying further research needs. Since children with hearing loss do not receive the same amount of exposure to speech and language as typically developing children, it can be expected that the development of speech and word recognition in this population may progress differently. If we can identify differences in auditory processing and phonological development in children with hearing impairment, we can modify speech and language therapy to focus on more specific and effective targets. The subsequent chapters will provide a critical review of the current literature on the aforementioned topics. In Chapters 2 and 3, studies assessing differences in processing, attention to sound, intersensory perception, and sound discrimination abilities in children with normal hearing and hearing impairment will be discussed. Chapters 4 and 5 focus on word recognition skills, and early lexical representations. Chapter 6 will synthesize results of available studies and suggest areas in which more research is needed. Together, these chapters will help us gain a better understanding of the complex interactions between auditory processing, executive functioning, phonological development and later word recognition outcomes. By identifying which avenues have the greatest effect on outcomes in cochlear implant users, we can modify speech and language therapy in order to address the unique needs of this special population. / text

The largest group of English language learners in the United States is comprised individuals who speak Spanish as a first language. There is a growing need for speech-language pathologists to better understand the language development of children learning two languages in order to distinguish between typical and disordered communication with this population. For monolingual English speakers, rate of grammatical morpheme acquisition is typically predicted based on MLU. In bilingual children, current language use has been determined to be a potentially more useful predictor of language performance. The purpose of this study was to determine English grammatical morpheme performance for English-Spanish bilingual preschool-age children based on their language exposure. Data was drawn from two existing data sets that included a total of 314 children. Their performance on the BESA was analyzed for grammatical morphemes in English. Interviews were conducted to determine language use and exposure. We present patterns of English grammatical morpheme acquisition in bilingual children as related to current language use. / text

The effectiveness of treatment approaches aimed at children with language impairments to improve reading skills is the focus of this research synthesis. Research in this area is extensive but this report aims to focus on the results of 12 studies to highlight similarities and differences. Findings from these studies were analyzed and showed that phonological awareness intervention is one of the most prevalent types of intervention for this population. Research supports the fact that phonological awareness intervention can produce positive changes in children with language impairments. This type of intervention can not only cause improvements in phonological awareness skills but can also cause increases in reading ability. Credibility ratings for the studies as well as clinical implications are also discussed. / text

This thesis extends a previous pilot study with children who stutter (CWS) to include children with specific language impairment (CSLI). The current study examines lexical-semantic organization in these two clinical populations in hopes of comparing and contrasting behavioral profiles. The study employed a list-recall task to assess the lexical-semantic organization of 9 CWS, 5 CSLI, and 20 typically developing children matched for age and vocabulary. Similar to previous investigations, our child participants demonstrated the well-documented list position effects. With regard to recall accuracy, by-participant analyses revealed significant differences between CSLI and their age-matched peers; however, they did not reveal significant differences between the CWS and either of their control groups nor between the CSLI and CWS groups. Further, inspection of error distribution suggested significant differences in the number and types of errors the CSLI and control groups produced. The prevalence of unrelated and previous list errors in CSLI suggest that deficits in inhibitory processes as well as perseveration may have affected their performance. Areas of overlap and divergence in the profiles of CWS and CSLI indicate continuity in the degree of lexical-semantic weakness as well as differences in lexical retrieval and executive functions among CSLI and CWS. / text

The data gathered from disability service professionals in six different states through an on-line survey and follow up interviews was used to determine if there was a correlation between specific professional practices and the magnitude of the disparity in four-year college graduation and employment rates between individuals with visual impairments and the general population.. The frequency of use of an individual professional practice that addressed technology that could be aligned with the social model disability was associated with reduced disparities in rates of employment and post-secondary graduation, as was an aggregate variable that represented the average frequency of use of professional practices that addressed concerns related to the attitudes of others; social connections; and access to the environment, print, and technology that could be aligned with the social model of disability. In addition, the professional practice that addressed environmental access concerns that could be aligned with the political model of disability was associated with reduced disparities post-secondary graduation rates and the professional practice that addressed access to print concerns that could be aligned with the social model of disability was associated with reduced disparities in rates of employment. Overall, participants cited personal professional experience as the main source of influence for initiating practices regardless of the model of disability with which each practice could be aligned. At the same time, participant responses suggested that those practices that could be aligned with the medical model were more likely to be known to the participant and originate from personal professional experiences than practices that aligned with the social model and the political model. The results from this study suggested that of the external influences, laws and regulations may have been the most influential in initiating practices that could be aligned with the social model of disability and subsequently associated with positive educational and employment outcomes. The data generated through the interviews reinforced the survey findings but also revealed pragmatic perspectives on disability that informed practice, including the use of multiple models of disability at the same time in response to individual situations.

Damage to the brain can affect the core of the individual, i.e. the self. Results from a small number of studies with amnesic individuals indicate that patients' ability to show preserved knowledge of self may vary. The present study explored self-knowledge in patients with memory impairment as a result of confabulation, mild cognitive impairment, Alzheimer's disease and acquired brain damage. We found that different memory disorders differentially affected patients' self-knowledge. At least some patients showed a preserved sense of self, and were able to acquire information about another person that they had met postmorbidly. Frontal function and stability of cognitive impairments over time appear to be two variables important in determining whether patients can have a consistent and updated sense of self. We also explored the extent to which self-referential and other-referential processing might enhance memory in individuals with memory-impairment. The self-reference effect (SRE) and other-reference effect (ORE) have been consistently found in normal adults. Results indicated that patients showed a normal SRE and ORE. The SRE and ORE appeared to be at least partly dependent on degree of knowledge of the person being referenced, and were also related to general memory and frontal function. Only the SRE, however, was also related to patients' ability to improve memory as a result of emotional processing. These findings may have important implications for caregivers and healthcare professionals working with memory-impaired patients, and may pave the way to novel memory rehabilitation methods.

This exploratory study investigated the techniques used by teachers of the visually impaired when administering math questions with graphics to students with blindness or low vision. The researcher observed and videotaped 10 pairs of students with visual impairments and their teachers while the students were taking a test that consisted of 12 graphic math items and found a wide variance existed between teachers in the administering of mathematical test items with graphics to their students. The most prevalent teacher behaviors observed were teacher initiation and graph detail description. For the majority of the teacher initiated responses, teachers gave information on a specific detail of the math graphic. Students predominantly asked for clarification regarding the math graphic itself or clarification of the math problem itself. Teachers used a variety of factors in determining if and when students required assistance during testing for large print or tactile graphics. No statistical significance was found between braille and large print groups with regard to teacher variation, student variation, and scores on test items, No relationship was found between correct answers on the test and teacher variation scores but a strong, positive correlation existed for total test time and teacher variation scores. In addition, there was no statistical significance, between the six math graph types used in this study. Hand movements of braille students were also observed, 90% of students using either both hands or mostly both hands when exploring the tactile graphic math problem. A horizontal movement was the primary direction students used when examining the tactile graphic. Recommendations were made regarding future research with large print and tactile graphics

The integrity of brain white matter is vital for the interneuronal signalling between distinct brain regions required for normal cognitive function. White matter integrity is compromised with ageing and could contribute to age-related cognitive decline. Chronic cerebral hypoperfusion is thought to underlie the development of white matter pathology and cognitive changes, often seen in the elderly. Additionally, the development of regional hypoperfusion and white matter damage are thought to be early events in Alzheimer’s disease (AD) pathogenesis. This thesis set out to test the hypothesis that chronic cerebral hypoperfusion underlies the development of white matter pathology and cognitive decline and also that chronic cerebral hypoperfusion causes the development of Ab pathology in AD. The first aim was to investigate the impact of hypoperfusion on the development of white matter damage and different aspects of cognition in a mouse model of chronic cerebral hypoperfusion. Two studies were undertaken to address this. The first study examined the temporal development of pathology following hypoperfusion induced by bilateral carotid artery stenosis (BCAS) using microcoils Hypoperfusion was induced in wild type (WT) mice and the pathological changes examined at one week, two weeks, one month and two months. Hypoperfused animals developed a diffuse and widespread white matter pathology, present from one week, which occurred predominantly in the myelin component of white matter; this was accompanied by minimal axonal damage. A second study examined the impact of hypoperfusion on different aspects of spatial memory and further investigated pathological changes in the model at one and two months. Behavioural testing revealed a significant impairment in spatial working memory but not episodic memory or spatial reference memory in hypoperfused animals. In the same mice, pathological assessment indicated that there was a significant increase in levels of myelin damage and elevated levels of microglial activation as compared to shams. These results demonstrate that modest reductions in cerebral blood flow are sufficient to cause the development of white matter damage and the development of cognitive deficits. The second aim was to investigate the impact of hypoperfusion on the development of white matter and amyloid pathology in a mouse model (3xTg-AD) of AD. To address this, using 2 different sizes of microcoils (0.18mm and 0.16mm internal diameter) BCAS of varying severities was induced in 3xTg-AD mice and white matter and Ab pathology were assessed at one month. Circle of Willis (CoW) architecture was also compared between WT and 3xTg-AD mice. Overall white matter pathology was not exacerbated in experimental 3xTg-AD mice with BCAS induced by 0.18mm coils. However with a greater level of stenosis (0.16mm coil) ischaemic damage to neuronal perikarya was present in most experimental animals. In addition to ischaemic damage, localised areas of severe white matter pathology were also observed in conjunction with subtle changes to white matter Ab levels. Hypoperfusion did not impact on the development of intraneuronal Ab pathology, other than in the presence of ischaemic damage when levels were reduced. Comparison of CoW architecture between WT and 3xTg-AD mice revealed strain specific differences in the presence and morphology of the posterior communicating artery which may explain the lack of pathology in 3xTg-AD mice as compared to WT following BCAS induced using 0.18mm dia. microcoils. The third aim was to investigate whether white matter protein composition changed with age and also whether ageing conferred increased vulnerability to hypoperfusion. To address this, white matter protein levels were compared between young (3-4 months) and old (12-13 months) 3xTg-AD mice. White matter pathology was compared between sham and hypoperfused animals in the aged cohort. Levels of myelin basic protein and 2', 3'-cyclic nucleotide 3'- phosphodiesterase were found to be significantly increased whilst levels of myelin associated glycoprotein were significantly reduced with ageing. These results suggest that changes in myelin protein composition may contribute to the development of age related white matter pathology. White matter pathology was not exacerbated in aged hypoperfused animals following one month of hypoperfusion as compared to shams. The results presented within the thesis demonstrate that chronic cerebral hypoperfusion precipitates the development of selective white matter damage and impacts on cognition. Also it has been shown that where hypoperfusion is severe enough to cause ischaemic damage to neuronal perikarya and localised areas of severe white matter pathology, alterations in white matter Ab levels can occur. Hypoperfusion does not impact on APP processing or on intraneuronal levels of APP or Ab, other than in the presence of ischaemic damage to neuronal perikarya, when levels are reduced. These findings highlight the importance of early intervention strategies in the treatment of vascular risk factors which can lead to hypoperfusion and the development of white matter damage and a decline in cognitive function in later life. These findings also suggest that repair or prevention of white matter damage may be an appropriate strategy for the attenuation of cognitive decline following onset of hypoperfusion. This thesis also highlights some of the limitations of animal models of human disease.

Children with Specific Language Impairment (SLI) often present with difficulties in learning new words compared to age-matched children with typical language development. These difficulties may affect the acquisition, storage, or retrieval of new words. Word-learning deficits impact on children’s vocabulary development and impede their language and literacy development. Findings from a wide range of studies investigating word-learning in children with SLI demonstrated that semantic and phonological knowledge are crucial to the word-learning process. However, intervention studies designed to improve the word-learning abilities in children with SLI are sparse. The experiments described in this thesis addressed this need to understand the effects of interventions on word-learning abilities. Further, the thesis describes the first investigation of word-learning abilities of New Zealand school-aged children with SLI. Specifically, the following three broad questions are asked: 1. What are the word-learning skills of New Zealand school-aged children with SLI compared to children with typical language development and which underlying language skills influence word-learning? 2. What are the immediate and longer term effects of phonological awareness and semantic intervention on word-learning and language skills in children with SLI? 3. What are the error patterns of children with SLI compared to children with typical language development when learning to produce new words and do these patterns change following phonological awareness and semantic intervention? The first experiment compared the word-learning abilities of 19 school-aged children with SLI (aged 6;2 to 8;3) to age-matched children with typical language development and revealed that children with SLI presented with significant difficulties to produce and to comprehend new words. After repeated exposure, children with SLI caught up to the performances of children with typical language development in learning to comprehend new words, but not on production of new words. Correlation analyses demonstrated that there were no correlations between the word-learning skills and other language measures for children with SLI, whereas the word-learning abilities of children with typical language development were correlated to their phonological awareness, semantic, and general language skills. In the second experiment, it was investigated whether there were also qualitative differences during word-learning between children with and without SLI additionally to the quantitative differences as revealed in the first experiment. Children’s erroneous responses during the word-learning tasks were categorised into phonological, semantic, substitution or random errors. A comparison of the children’s error patterns revealed that children with SLI presented with a different error pattern and made significantly more random errors than children with typical language development. However, after repeated exposure, children with SLI demonstrated a similar error pattern as children without SLI. Furthermore, it was examined whether a specific combination of phonological and semantic cues facilitated children’s learning of new words or whether there were word-specific features that facilitated children’s word-learning. No facilitative word-specific features could be identified. Analysis revealed that there were no significant effects of cueing on learning new words, but specific patterns could be derived for children with SLI. Children with SLI learned to comprehend more words that were presented with two semantic cues or one phonological and one semantic cue and learned to produce more words that were presented with two phonological cues. In the third experiment, the effectiveness of a combined phonological awareness and semantic intervention to advance children’s word-learning abilities was examined. Nineteen children with SLI (same participants as in experiment 1) participated in this intervention study that implemented an alternating treatment group design with random assignment of the participants. Children in group A received phonological awareness intervention followed by semantic intervention, whereas children in group B received the same interventions in the reverse order. Children’s word-learning abilities were assessed at pre-test, prior to the intervention, at mid-test after intervention phase 1, and at post-test, immediately following the completion of the second intervention phase. Each intervention itself was effective in significantly improving children’s fast mapping skills, however, gains in children’s word-learning abilities were only found for children in group A for production of new words. Extending the findings of the intervention effectiveness of phonological awareness and semantic intervention on word-learning as reported in experiment 3, it was investigated in experiment 4, whether the implemented intervention additionally influenced the error patterns of children with SLI. The erroneous responses of children with SLI on all word-learning probes at pre-, mid-, and post-test were categorised into the same error groups as described in the second experiment (semantic, phonological, substitution, and random errors). The error analyses revealed that children’s error profiles changed during the course of intervention and treatment specific effects on children’s erroneous responses were found. Post-intervention, children who received phonological awareness followed by semantic intervention displayed the same error patterns as children with typical language development, whereas children who received the same interventions in the reverse order maintained the same error pattern as displayed at pre-test. The final experiment examined the longer-term effects of the combined phonological awareness and semantic intervention reported in experiment 3 on the language and literacy development of children with SLI. Eighteen of the 19 children with SLI, who received the intervention reported in experiment 3, were available for re-assessment 6 months after the completion of the intervention. The children (aged 7;1 to 9;2 years) were re-assessed on a range of standardised and experimental measures. Data analysis revealed that 6 months post-intervention, all children were able to maintain their gains in phonological awareness, semantic, and decoding skills as displayed immediately after the intervention. Children’s general language and reading skills significantly improved following the intervention; however, children who received phonological awareness intervention followed by semantic intervention displayed significantly better reading outcomes than the children who received the same interventions in the reverse order. This thesis revealed that a combination of phonological awareness and semantic intervention can enhance the word-learning abilities of children with SLI. The combined intervention approach was also effective in additionally improving children’s general language skills and the reading of single non-words and real words, as well as connected text. The immediate and longer-term intervention effects provide evidence that advancing the semantic and phonological awareness skills is an effective intervention approach to support children with SLI in their word-learning and to furthermore promote their language and literacy development. However, the order of the implemented interventions played a significant role: Children in the current study profited most when they received phonological awareness intervention first, followed by semantic intervention.

The aim of this study is to establish a brief screening tool to classify PD patients as PD with normal cognition (PD-N), PD patients with mild cognitive impairment (PD-MCI) and PD patients with dementia (PD-D). There has been emerging evidence that the MoCA (Montreal Cognitive Assessment) shows potential for the brief assessment of cognition to differentiate among PD patients. One possible solution to further improve the discrimination among PD-D, PD-MCI and PD-N groups is to examine Instrumental Activities of Daily Living (IADL) measures in conjunction with the MoCA. A convenience sample of 162 patients suffering from PD and 53 volunteer control subjects were examined in a movement disorders center. Extensive neuropsychological testing was done to classify the PD patients into PD-N, PD-MCI or PD-D. The 24 patients were diagnosed as PD-D based on the Movement Disorders Society Task Force criteria. For PD-MCI, two criteria were used: 1.5SD:2 in one-domain (1.5 SD below the norms on two measures in at least one of four cognitive domains) and 1.5SD:1 in two-domains (1.5 SD below normative data in at least one measure but in two domains) which made a diagnosis of 34 and 39 PD-MCI patients respectively. The remaining patients were classified as PD-N. For both the MCI criteria, the results suggest that 1) for discriminating PD-MCI from PD-N, the MoCA is a sufficiently suitable screening measure that is not improved by adding ADL measures, 2) for distinguishing PD-D from PD-MCI, the MoCA and the full ADL-IS questionnaire can be administered to a patient suffering from PD. When time is limited and depending on the possibility of answering the questions regarding the ADL-IS items, the MoCA along with the Muddled and Complex Medication ADL-IS items should be administered. When no scores are obtained for Muddled, then MoCA along with Complex Medication ADL-IS item is sufficient to discriminate PD-D from PD-MCI. However, if no scores are obtained for Complex Medication item, then an average of four ADL-IS items should be taken along with the MoCA. This attractive brief screening tool helps in detection of cognitive impairment in the elderly.